1. Field of the Invention
The present invention relates to a plasma display panel (PDP), and more particularly, to a PDP and method for fabricating the same having improved discharge stability and discharge efficiency.
2. Description of the Related Art
Generally, a PDP forms an image by generating a glow discharge by applying a voltage to electrodes, installed in a gas-filled sealed space, to excite a phosphor layer using ultraviolet rays generated during the glow discharge operation.
A PDP may be classified as a direct current (DC), alternating current (AC), or hybrid type according its driving method, and it may also be classified as a two-electrode or three-electrode type according to the number of electrodes. The DC type includes an auxiliary electrode for inducing an auxiliary discharge, and the AC type includes an address electrode for improving address speed by dividing address and sustain discharges.
The AC type may be classified as an opposed discharge or a surface discharge type according to an arrangement of the discharge performing electrodes. The opposed discharge type includes two discharge sustain electrodes disposed on facing substrates to generate the discharge perpendicularly to the panel, and the surface discharge type includes two discharge sustain electrodes disposed on the same substrate to generate the discharge on a plane of the substrate.
In a PDP having the above structure, discharge cells are disposed between the substrates, and FIG. 1 shows a cross section of a unit discharge cell.
Referring to FIG. 1, in a discharge cell 10, a sustain electrode 12, which includes an X electrode 13 and a Y electrode 14, is formed on a lower surface of a first substrate 11. The X electrode 13 and the Y electrode 14 function as a common electrode and a scan electrode, respectively, and they are separated from each other by a discharge gap g.
The X electrode 13 and the Y electrode 14 respectively include transparent electrodes 13a and 14a and bus electrodes 13b and 14b, which are formed on lower surfaces of the transparent electrodes 13a and 14a to apply voltages. A first dielectric layer 15 covers the sustain electrode 12, and a protective layer 16 covers the first dielectric layer 15.
A second substrate 21 faces the first substrate 11, and an address electrode 22 is formed on the second substrate 21. A second dielectric layer 23 covers the address electrode 22. A phosphor layer 24 is formed on the second dielectric layer 23, and a discharge gas is injected into the discharge cell 10.
Applying an address voltage between the address electrode 22 and the Y electrode 14 addresses the discharge cell 10 and forms a wall charge in it. Applying a sustain voltage between the X electrode 13 and the Y electrode 14 of the addressed discharge cell 10 causes a sustain discharge. The discharge generates electric charges that collide with the discharge gas to form the plasma and ultraviolet rays. The ultraviolet rays excite the fluorescent material on the phosphor layer 24 to display an image.
The discharge between the X electrode 13 and the Y electrode 14 starts at the discharge gap g and diffuses along the surfaces of the X electrode 13 and the Y electrode 14 from the discharge gap g. The discharge does not diffuse when a voltage difference between the X electrode 13 and the Y electrode 14 is less than a discharge start voltage. A dotted line in FIG. 1 shows a sustain discharge path that is formed in the discharge cell 10.
If the discharge cell 10 is not high enough, the discharge path may contact the phosphor layer 24, thereby degrading discharge efficiency. Further, ions generated in the discharge process that collide with the phosphor layer 24 reduce the layer's life span. However, if the discharge cell 10 is too high, it negatively affects the address discharge.
Therefore, there is a need to design a panel having optimally set widths of the X electrode 13 and the Y electrode 14 and height of the discharge cell 10. Japanese Laid-open Patent Publication No. 1997-330663 discloses a PDP design.
Another important element in PDP design is a partial pressure of Xe that may be included in the discharge gas.
Specifically, the discharge gas injected in the discharge cell may be formed by mixing He, Ne, and Xe, and increasing the partial pressure of Xe may improve discharge efficiency, reduce power consumption, and increase brightness.
On the other hand, an increased partial pressure of Xe may require a higher discharge voltage, which results in more active ion movements in the discharge cell and increased impacts caused by the ions contacting the phosphor layer. Further, increasing the partial pressure of Xe may reduce the address voltage margin. Thus, an optimal design of the panel is required when increasing the partial pressure of Xe.